• Atmosphere
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• v.34 no.4
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• pp.445-462
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• 2024

This study analyzes and compares the results of airborne snowfall enhancement experiments conducted on November 25 and 28, 2019, as part of the International Joint Cloud Observation and Weather Control Experiment (IJCO-WCE) 2019 campaign. The objective was to assess the effects of experimental interventions on cloud precipitation patterns. To address the challenges in verifying artificial snowfall enhancement, this study proposes an innovative approach, utilizing a post-experiment zigzag flight path for in-situ observations. This approach allowed for detailed comparisons between affected and unaffected cloud regions. Precipitation was observed in the target area on the leeward side on November 25, whereas no precipitation was recorded during the November 28 experiment. We concluded that airborne snowfall enhancement is more effective when the lower atmosphere is unstable at the rear of a trough, as confirmed by changes in the distribution of precipitation particles in the clouds and on the ground. Two identical flight experiments were conducted using the KMA/NIMS atmospheric research aircraft, allowing detailed observations. Data collected from onboard cloud observation instruments and six ground stations facilitated detailed analyses of changes in the concentration and size distribution of cloud particles (e.g., supercooled droplets, ice crystals, and snow particles). The method of comparing particle sizes between clouds affected and unaffected by the experiments is used to verify the effectiveness of artificial snowfall enhancement techniques. This methodology could be widely adopted in future studies to improve our understanding of weather modification strategies.